7-alkylidene-3-substituted-3-cephem-4-carboxylates as beta-lactamase inhibitors

ABSTRACT

The invention provides compounds of formula (I):  
                 
 
wherein: R 1 —R 4  and A have any of the values defined in the specification, and their pharmaceutically acceptable salts, are useful for inhibiting β-lactamase enzymes, for enhancing the activity of β-lactam antibiotics, and for treating β-lactam resistant bacterial infections in a mammal. The invention also provides pharmaceutical compositions, processes for preparing compounds of formula (I), and intermediates useful for the synthesis of compounds of formula (I).

RELATED APPLICATIONS

This application is a continuation under 37 C.F.R. 1.53(b) of U.S.patent application Ser. No. 10/202,405 filed Jul. 24, 2002, which claimsthe benefit of U.S. Provisional Application No. 60/307,403 filed Jul.24, 2001, which applications are incorporated herein by reference andmade a part hereof.

STATEMENT OF GOVERNMENT RIGHTS

This invention was made, at least in part, with a grant from theGovernment of the United States of America (Grant No.1 R41 AI48997-01from the National Institutes of Health). The Government may have certainrights to the invention.

BACKGROUND OF THE INVENTION

The most important mechanism of microbial resistance to β-lactamantibiotics is the bacterial production of β-lactamases, enzymes whichhydrolytically destroy β-lactam antibiotics, such as penicillins andcephalosporins. This type of resistance can be transferred horizontallyby plasmids that are capable of rapidly spreading the resistance, notonly to other members of the same strain, but even to other species. Dueto such rapid gene transfer, a patient can become infected withdifferent organisms, each possessing the same β-lactamase.

β-lactamase enzymes have been organized into four molecular classes: A,B, C, and D based on amino acid sequence. Class A, which includes RTEMand the β-lactamase of Staphylococcus aureus, class C, which includesthe lactamase derived from P-99 Enterobacter cloacae, and class D areserine hydrolases. Class A enzymes have a molecular weight of about 29kDa and preferentially hydrolyze penicillins. The class B lactamases aremetalloenzymes and have a broader substrate profile than the proteins inthe other classes. Class C enzymes include the chromosomalcephalosporinases of Gram-negative bacteria and have molecular weightsof approximately 39 kDa. The recently recognized class D enzymes exhibita unique substrate profile which differs significantly from both class Aand class C.

The class C cephalosporinases, in particular, are responsible for theresistance of gram negative bacteria to a variety of both traditionaland newly designed antibiotics. The Enterobacter species, whichpossesses a class C enzyme, is now the third greatest cause ofnosocomial infections in the United States. This class of enzymes oftenhas poor affinities for inhibitors of the class A enzymes, such asclavulanic acid, a commonly prescribed inhibitor, and to common in vitroinactivators, such as 6-β-iodopenicillanate.

One strategy for overcoming this rapidly evolving bacterial resistanceis the synthesis and administration of β-lactamase inhibitors.Frequently, β-lactamase inhibitors do not possess antibiotic activitythemselves and are thus administered together with an antibiotic. Oneexample of such a synergistic mixture is the product sold under thetrademark AUGMENTIN (amoxicillin, clavulanate potassium), which containsthe antibiotic amoxicillin and the β-lactamase inhibitor, clavulanatepotassium.

There is a continued need for novel β-lactamase inhibitors, and inparticular, for β-lactamase inhibitors that can be coadministered with aβ-lactam antibiotic.

SUMMARY OF THE INVENTION

The invention also provides a compound of formula (I):

wherein:

-   -   R₁ and R₂ are each independently hydrogen, (C₁-C₁₀)alkyl,        (C₂-C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₃-C₈)cycloalkyl,        (C₁-C₁₀)alkoxy, (C₁-C₁₀)alkanoyl, (C₁-C₁₀)alkanoyloxy,        (C₁-C₁₀)alkoxycarbonyl, aryl, heterocycle, halo, cyano, nitro,        —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g), NR_(f)R_(g),        or —S(O)_(n)R_(h);    -   R₃ is hydrogen, halo, aryl, heteroaryl, —S(O)_(n)R_(h,), or        —CH═CHC(═O)NR_(m)R_(p);    -   R₄ is hydrogen;    -   A is thio, sulfinyl, or sulfonyl;    -   each n is independently 0, 1, or 2;    -   each R_(e) is independently hydrogen, or (C₁-C₁₀)alkyl;    -   each R_(f) and R_(g) is independently hydrogen, (C₁-C₁₀)alkyl,        (C₁-C₁₀)alkoxy, phenyl, benzyl, phenethyl, (C₁-C₁₀)alkanoyl,        or-C(═O)NR_(f)R_(g) wherein R_(f) and R_(g) form a ring        optionally containing a nitrogen atom in the ring —NR_(e)—;    -   each R_(h) is independently (C₁-C₁₀)alkyl, or aryl; and    -   R_(m) is hydrogen, and R_(p) is NH₂, OH, (C₂-C₁₀)cycloalkyl, or        —(C₂-C₁₀)alkyl-NH₂; or R_(m) and R_(p) together with the        nitrogen to which they are attached form a piperidine,        morpholine, thiomorpholine, pyrrolidine, or piperazine ring,        wherein the piperazine is substituted at the 4-position with        hydrogen or a (C₁-C₁₀)alkyl;    -   wherein any (C₁-C₁₀)alkyl, (C₂-C₁₀)alkenyl, (C₂-C₁₀)alkynyl,        (C₃-C₈)cycloalkyl, (C₁-C₁₀)alkoxy, (C₁-C₁₀)alkanoyl,        (C₁-C₁₀)alkanoyloxy, or (C₁-C₁₀)alkoxycarbonyl of R₁ or R₂ is        optionally substituted with one or more, substituents        independently selected from halo, hydroxy, cyano, cyanato,        nitro, mercapto, oxo, aryl, heterocycle, (C₂-C₆)alkenyl,        (C₂-C₆)alkynyl, (C₁-C₆)alkoxy, (C₁-C₆)alkanoyl,        (C₁-C₆)alkanoyloxy, aryl(C₁-C₆)alkanoyloxy,        halo(C₁-C₆)alkanoyloxy, heterocycle(C₁-C₆)alkanoyloxy, aryloxy,        (heterocycle)oxy, (C₃-C₈)cycloalkyl, —COOR_(e),        —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g), —NR_(h)R_(i), or        —S(O)_(n)R_(k); and    -   wherein any aryl is optionally substituted with one or more        substituents independently selected from halo, hydroxy, cyano,        trifluoromethyl, nitro, trifluoromethoxy, (C₁-C₆)alkyl,        (C₁-C₆)alkanoyl, (C₁-C₆)alkanoyloxy, (C₁-C₆)alkoxycarbonyl,        —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g), NR_(h)R_(i),        or —S(O)_(n)R_(k); or a pharmaceutically acceptable salt        thereof.

The invention provides a pharmaceutical composition comprising acompound of formula (I), or a pharmaceutically acceptable salt thereof,in combination with a pharmaceutically acceptable diluent or carrier, aswell as such a pharmaceutical composition that further comprises aβ-lactam antibiotic.

The invention also provides a method comprising inhibiting a β-lactamaseby contacting (in vitro or in vivo) the β-lactamase with an effectiveamount of a compound of formula (I); or a pharmaceutically acceptablesalt thereof.

The invention also provides a therapeutic method comprising inhibiting aβ-lactamase in a mammal in need of such therapy, by administering aneffective inhibitory amount of a compound of formula (I); or apharmaceutically acceptable salt thereof.

The invention also provides a method comprising enhancing the activityof a β-lactam antibiotic, by administering the β-lactam antibiotic to amammal in need thereof, in combination with an effective β-lactamaseinhibiting amount of a compound of formula (I); or a pharmaceuticallyacceptable salt thereof.

The invention also provides a method comprising treating a β-lactamresistant bacterial infection in a mammal, by administering an effectiveamount of a β-lactam antibiotic in combination with an effectiveβ-lactamase inhibiting amount of a compound of formula (I); or apharmaceutically acceptable salt thereof.

The invention also provides a compound of formula (I) for use in medicaltherapy (preferably for use in inhibiting a β-lactamase in a mammal, orfor treating a β-lactam resistant bacterial infection in a mammal), aswell as the use of a compound of formula (I) for the manufacture of amedicament useful for inhibiting a β-lactamase in a human.

The invention also provides processes and intermediates disclosed hereinthat are useful for preparing β-lactamase inhibitors of formula (I).

Compounds of formula (I) are useful as β-lactamase inhibitors fortherapeutic applications. They are also useful as pharmacological toolsfor in vitro or in vivo studies to investigate the mechanisms ofantibiotic resistance, to help identify other therapeutic antibioticagents or β-lactamase inhibitors, to identify which β-lactamases arebeing expressed by a given microorganism, or to selectively inhibit oneor more β-lactamases in a microorganism.

BRIEF DESCRIPTION OF FIGURES

FIGS. 1-6 illustrate the preparation of representative compounds of theinvention.

DETAILED DESCRIPTION

The following definitions are used, unless otherwise described: halo isfluoro, chloro, bromo, or iodo. Alkyl, alkoxy, alkenyl, and the like,denote both straight and branched groups. Aryl denote a phenyl radical,or an ortho-fused bicyclic carbocyclic radical having about nine to tenring atoms in which at least one ring is aromatic. Heterocycle denotes a6-10 membered unsaturated or saturated mono-bi- or tri-cyclic ringsystem comprising carbon and 1, 2, 3, or 4 heteroatoms selected from thegroup consisting of non-peroxide oxygen, sulfur, and N(X) wherein each Xis absent or is H, O, (C₁-C₄)alkyl, phenyl or benzyl. The term“heterocycle” includes “Heteroaryl,” which denotes a radical attachedvia a ring carbon of a monocyclic aromatic ring containing five or sixring atoms consisting of carbon and one to four heteroatoms eachselected from the group consisting of non-peroxide oxygen, sulfur, andN(X) wherein each X is absent or is H, O, (C₁-C₄)alkyl, phenyl orbenzyl, as well as a radical of an ortho-fused bicyclic heterocycle ofabout eight to ten ring atoms derived therefrom, particularly abenz-derivative or one derived by fusing a propylene, trimethylene, ortetramethylene diradical thereto. A preferred heteroaryl is, forexample, a pyridyl radical.

The term “enhancing” the activity of a β-lactam antibiotic meansimproving or increasing the antibiotic activity of the compared in astatistically measurable and significant manner with respect to theactivity demonstrated by the compound in the absence of a compound ofthe invention.

The letters “BH” or “bhl” represent a benzhydryl ester.

It will be appreciated by those skilled in the art that compounds of theinvention having a chiral center may exist in and be isolated inoptically active and racemic forms. Some compounds may exhibitpolymorphism. It is to be understood that the present inventionencompasses any racemic, optically-active, polymorphic, orstereoisomeric form, or mixtures thereof, of a compound of theinvention, which possess the useful properties described herein, itbeing well known in the art how to prepare optically active forms (forexample, by resolution of the racemic form by recrystallizationtechniques, by synthesis from optically-active starting materials, bychiral synthesis, or by chromatographic separation using a chiralstationary phase) and how to determine β-lactamase inhibitory activityusing the standard tests described herein, or using other similar testswhich are well known in the art.

Specific values listed below for radicals, substituents and ranges, arefor illustration only; they do not exclude other defined values or othervalues within defined ranges for the radicals and substituents.

Specifically, (C₁-C₆)alkyl can be methyl, ethyl, propyl, isopropyl,butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl, or hexyl; (C₁-C₁₀)alkylcan be methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl,pentyl, 3-pentyl, hexyl, heptyl, octyl, nonyl, or decyl;(C₃-C₈)cycloalkyl can be cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, or cyclooctyl; (C₁-C₁₀)alkoxy can be methoxy,ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, sec-butoxy, pentoxy,3-pentoxy, hexyloxy, heptyloxy, octyloxy, nonyloxy or decyloxy;(C₁-C₆)alkoxy can be methoxy, ethoxy, propoxy, isopropoxy, butoxy,iso-butoxy, sec-butoxy, pentoxy, 3-pentoxy, or hexyloxy; (C₂-C₁₀)alkenylcan be vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl,1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl,3-hexenyl, 4-hexenyl, 5-hexenyl, 1-heptenyl, 2-heptenyl, 3-heptenyl,4-heptenyl, 5-heptenyl, 6-heptenyl, 1-octenyl, 2-octenyl, 3-octenyl,4-octenyl, 5-octenyl, 6-octenyl, 7-octenyl, 1-nonenyl, 2-nonenyl,3-nonenyl, 4-nonenyl, 5-nonenyl, 6-nonenyl, 7-nonenyl, 8-nonenyl,1-decenyl, 2-decenyl, 3-decenyl, 4-decenyl, 5-decenyl, 6-decenyl,7-decenyl, 8-decenyl, or 9-decenyl; (C₂-C₁₀)alkynyl can be ethynyl,1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl,2-pentynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl,4-hexynyl, 5-hexynyl, 1-heptynyl, 2-heptynyl, 3-heptynyl, 4-heptynyl,5-heptynyl, 6-heptynyl, 1-octynyl, 2-octynyl, 3-octynyl, 4-octynyl,5-octynyl, 6-octynyl, 7-octynyl, 1-nonynyl, 2-nonynyl, 3-nonynyl,4-nonynyl, 5-nonynyl, 6-nonynyl, 7-nonynyl, 8-nonynyl, 1-decynyl,2-decynyl, 3-decynyl, 4-decynyl, 5-decynyl, 6-decynyl, 7-decynyl,8-decynyl, or 9-decynyl; (C₁-C₁₀)alkanoyl can be acetyl, propanoyl,butanoyl, pentanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, ordecanoyl; (C₁-C₁₀)alkoxycarbonyl can be methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, pentoxycarbonyl,hexyloxycarbonyl, heptyloxycarbonyl, octyloxycarbonyl, nonyloxycarbonylor decyloxycarbonyl; (C₁-C₁₀)alkanoyloxy can be formyloxy, acetoxy,propanoyloxy, butanoyloxy, isobutanoyloxy, pentanoyloxy, hexanoyloxy,heptanoyloxy, octanoyloxy, nonanoyloxy, or decanoyloxy; aryl can bephenyl, indenyl, or naphthyl; heterocycle can benztriazolyl, triazinyl,oxazoyl, isoxazolyl, oxazolidinoyl, isoxazolidinoyl, thiazolyl,isothiazoyl, pyrazolyl, imidazolyl, pyrrolyl, pyrazinyl, pyridinyl,morpholinyl, quinolinyl, isoquinolinyl, indolyl, pyrimidinyl,piperidinyl, pyrrolidinyl, morpholinyl, thiomorpholinyl, or piperazinyl;and heteroaryl can be, for example, furyl, imidazolyl, triazolyl,triazinyl, oxazoyl, isoxazoyl, thiazolyl, isothiazoyl, pyrazolyl,pyrrolyl, pyrazinyl, tetrazolyl, 1-methyl-1H-tetrazol-5-yl, pyridyl, (orits N-oxide), thienyl, pyrimidinyl (or its N-oxide), indolyl,isoquinolyl (or its N-oxide) or quinolyl (or its N-oxide).

In one embodiment, the invention provides a compound of formula (I):

wherein:

-   -   R₁ and R₂ are each independently hydrogen, (C₁-C₁₀)alkyl,        (C₂-C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₃-C₈)cycloalkyl,        (C₁-C₁₀)alkoxy, (C₁-C₁₀)alkanoyl, (C₁-C₁₀)alkanoyloxy,        (C₁-C₁₀)alkoxycarbonyl, aryl, heteroaryl, heterocycle, halo,        cyano, nitro, —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g),        NR_(f)R_(g), or —S(O)_(n)R_(h);    -   R₃ is hydrogen, halo, aryl, heteroaryl, heterocycle, —Sn(R₅)₃,        —SAr, —S(O)_(n)Ar, —S(O)_(n)R_(h), —S(O)_(n)NH₂,        —S(O)_(n)NHR_(f), —S(O)_(n)NR_(f)R_(g), —COOR_(m), —C(═O)—R_(h),        —C(═O)NR_(f)R_(g), —CH═NOR_(i), —CH═CR_(j)R_(k), or cyano;    -   R₄ is hydrogen, aryl, heterocycle, (C₁-C₁₀)alkyl, benzyl,        phenethyl, -diaryl substituted(C₁-C₁₀)alkyl, such as —CHAr₂ or        —CHPh₂;    -   each R₅ is independently —(C₁-C₁₀)alkyl, (C₁-C₁₀)alkoxy, phenyl,        benzyl, phenethyl;    -   A is thio, sulfinyl, or sulfonyl;    -   each n is independently 0, 1, or 2;    -   each R_(e) is independently hydrogen, or (C₁-C₁₀)alkyl;    -   each R_(f) and R_(g) is independently hydrogen, (C₁-C₁₀)alkyl,        (C₁-C₁₀)alkoxy, phenyl, benzyl, phenethyl, (C₁-C₁₀)alkanoyl, or        —C(═O)NR_(f)R_(g) wherein R_(f) and R_(g) form a ring optionally        containing a nitrogen atom in the ring —NR_(e)—;    -   each R_(h) is independently (C₁-C₁₀)alkyl, phenyl,        aryl(C₁-C₆)alkyl, heteroaryl, heterocycle, or        heterocycle(C₁-C₆)alkyl;    -   R_(i) is hydrogen or (C₁-C₆)alkyl; and    -   R_(j) and R_(k) are each independently hydrogen, halo, cyano,        nitro, aryl, heterocycle, (C₂-C₆)alkenyl, —COOR_(e),        —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g), NR_(f)R_(g), or        —S(O)_(n)R_(h);    -   R_(m) is —H, —Na, —K, —Li, and like pharmaceutically acceptable        salts, —(C₁-C₁₀)alkyl, —(C₁-C₁₀)cycloalkyl, benzyl, phenethyl,        -diaryl substituted(C₁-C₁₀)alkyl, such as —CHAr₂ or —CHPh₂;    -   wherein any (C₁-C₁₀)alkyl, (C₂-C₁₀)alkenyl, (C₂-C₁₀)alkynyl,        (C₃-C₈)cycloalkyl, (C₁-C₁₀)alkoxy, (C₁-C₁₀)alkanoyl,        (C₁-C₁₀)alkanoyloxy, or (C₁-C₁₀)alkoxycarbonyl of R₁, R₂, R₅,        R_(j) and R_(k) is optionally substituted with one or more,        substituents independently selected from halo, hydroxy, cyano,        cyanato, nitro, mercapto, oxo, aryl, heterocycle,        (C₂-C₆)alkenyl, (C₂-C₆)alkynyl, (C₁-C₆)alkoxy, (C₁-C₆)alkanoyl,        (C₁-C₆)alkanoyloxy, aryl(C₁-C₆)alkanoyloxy,        halo(C₁-C₆)alkanoyloxy, heterocycle(C₁-C₆)alkanoyloxy, aryloxy,        (heterocycle)oxy, (C₃-C₈)cycloalkyl, —COOR_(e),        —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g), —NR_(h)R_(i), or        —S(O)_(n)R_(k); and    -   wherein any aryl is optionally substituted with one or more        substituents independently selected from halo, hydroxy, cyano,        trifluoromethyl, nitro, trifluoromethoxy, (C₁-C₆)alkyl,        (C₁-C₆)alkanoyl, (C₁-C₆)alkanoyloxy, (C₁-C₆)alkoxycarbonyl,        —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g), NR_(h)R_(i),        or —S(O)_(n)R_(k); or a pharmaceutically acceptable salt        thereof.

Specifically, A is sulfonyl (—SO₂—).

Specifically, R₁ is aryl, heterocycle, or —COOR_(e).

Specifically, R₁ is 2-pyridyl, or —COOR_(e).

Specifically, R₂ is hydrogen.

Specifically, R₃ is hydrogen, halo, aryl, heterocycle, —Sn(R₅)₃, —SAr,—S(O)_(n)Ar, —S(O)_(n)R_(h), —S(O)_(n)NH₂, —S(O)_(n)NHR_(f),—S(O)_(n)NR_(f)R_(g), —COOR_(m), —C(═O)—R_(h), or —C(═O)NR_(f)R_(g).

Specifically, R₃ is hydrogen, aryl, heterocycle, —Sn(R₅)₃, —SAr,—S(O)_(n)Ar, —S(O)_(n)R_(h), —S(O)_(n)NH₂, —S(O)_(n)NHR_(f), or—S(O)_(n)NR_(f)R_(g).

Specifically, R_(j) and R_(k) are each independently hydrogen, cyano,—COOR_(e), (C₂-C₁₀)alkenyl, or heteroaryl.

A specific compound of formula (I) is a compound of wherein: R₁ and R₂are each independently hydrogen, (C₁-C₁₀)alkyl, (C₂-C₁₀)alkenyl,(C₂-C₁₀)alkynyl, (C₃-C₈)cycloalkyl, (C₁-C₁₀)alkoxy, (C₁-C₁₀)alkanoyl,(C₁-C₁₀)alkanoyloxy, (C₁-C₁₀)alkoxycarbonyl, aryl, heteroaryl,heterocycle, halo, cyano, nitro, —COOR_(e), —C(═O)NR_(f)R_(g),—OC(═O)NR_(f)R_(g), NR_(f)R_(g), or —S(O)_(n)R_(h); R₃ is independentlyhydrogen, fluoro, —SPh, —SO₂Ar, —Sn(CH₃)₃, or —CH═CH—CO₂H; R₄ isindependently hydrogen, phenyl, heterocycle, (C₁-C₁₀)alkyl, benzyl,phenethyl, or —CHPh₂; A is thio, sulfinyl, or sulfonyl; each n isindependently 0, 1, or 2; each R_(e) is independently hydrogen, or(C₁-C₁₀)alkyl; each R_(f) and R_(g) is independently hydrogen,(C₁-C₁₀)alkyl, (C₁-C₁₀)alkoxy, phenyl, benzyl, phenethyl,(C₁-C₁₀)alkanoyl, or-C(═O)NR_(f)R_(g) wherein R_(f) and R_(g) form aring optionally containing a nitrogen atom in the ring —NR_(e)—; eachR_(h) is independently (C₁-C₁₀)alkyl, phenyl, aryl(C₁-C₆)alkyl,heterocycle, or heterocycle(C₁-C₆)alkyl; R_(i) is hydrogen or(C₁-C₆)alkyl; and R_(j) and R_(k) are each independently hydrogen, halo,cyano, nitro, aryl, heterocycle, (C₂-C₆)alkenyl, —COOR_(e),—C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g), NR_(f)R_(g), or —S(O)_(n)R_(h);wherein any (C₁-C₁₀)alkyl, (C₂-C₁₀)alkenyl, (C₂-C₁₀)alkynyl,(C₃-C₈)cycloalkyl, (C₁-C₁₀)alkoxy, (C₁-C₁₀)alkanoyl,(C₁-C₁₀)alkanoyloxy, or (C₁-C₁₀)alkoxycarbonyl of R₁, R₂, R_(j) andR_(k) is optionally substituted with one or more substituentsindependently selected from halo, hydroxy, cyano, cyanato, nitro,mercapto, oxo, aryl, heterocycle, (C₂-C₆)alkenyl, (C₂-C₆)alkynyl,(C₁-C₆)alkoxy, (C₁-C₆)alkanoyl, (C₁-C₆)alkanoyloxy,aryl(C₁-C₆)alkanoyloxy, halo(C₁-C₆)alkanoyloxy,heterocycle(C₁-C₆)alkanoyloxy, aryloxy, (heterocycle)oxy,(C₃-C₈)cycloalkyl, —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g),NR_(h)R_(i), or —S(O)_(n)R_(k); and wherein any aryl is optionallysubstituted with one or more substituents independently selected fromhalo, hydroxy, cyano, trifluoromethyl, nitro, trifluoromethoxy,(C₁-C₆)alkyl, (C₁-C₆)alkanoyl, (C₁-C₆)alkanoyloxy,(C₁-C₆)alkoxycarbonyl, —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g),NR_(h)R_(i), or —S(O)_(n)R_(k); or a pharmaceutically acceptable saltthereof.

Another specific compound is a compound wherein one of R_(j) and R_(k)is hydrogen and the other is cyano, —COOR_(e), (C₂-C₁₀)alkenyl, orheteroaryl.

Another specific compound is a compound wherein R_(j) is hydrogen orhalo, and R_(k) is cyano, methoxycarbonyl, aminocarbonyl,tert-butoxycarbonyl, 2-pyridyl-N-oxide, nitro, or vinyl.

Another specific compound is a compound wherein A is sulfonyl; R₁ is2-pyridyl, carboxy or tert-butoxy carbonyl; R₂ is hydrogen; R₃ ishydrogen, fluoro, —SPh, —SO₂Ph, —Sn(R₅)₃, or —CH═CH—CO₂H; and R₄ ishydrogen, —CHAr₂, or a pharmaceutically acceptable salt.

More specifically, R_(j) and R_(k) are each independently hydrogen,cyano, 2-(methoxycarbonyl), 2-pyridyl-N-oxide, or vinyl.

Another specific compound is a compound of formula (I) wherein A issulfonyl (—SO₂—); R₁ is 2-pyridyl, carboxy or tert-butoxycarbonyl; R₂ ishydrogen; and R₃ is hydrogen, halo such as fluoro, —SAr such as —SPh,—Sn(R₅)₃, cyano, —S(O)_(n)Ar; —CH═NOR_(i), or —CH═CR_(j)R_(k); or apharmaceutically acceptable salt thereof.

A more specific compound of formula (I) is a pharmaceutically acceptablesalt formed from a carboxylic acid of formula (I) wherein R₄ ishydrogen. Most preferred is a salt wherein R₄ been replaced with asodium or potassium ion. The term pharmaceutically acceptable salts alsoincludes poly salts (e.g. di- or tri-salts) of a compound of formula(I).

Processes and novel intermediates useful for preparing compounds offormula (I) are provided as further embodiments of the invention and areillustrated by the following procedures in which the meanings of thegeneric radicals are as given above unless otherwise qualified.

Representative compounds were prepared as indicated in FIGS. 1 to 6.Commercially available 3-hydroxy-3-cephem 1 was converted to halides 3a,3b, and 3c by employing the method of Farina (Farina et. al., J. Org.Chem. 54, 4962-4966 (1989)). The phenylacetyl group was removed upontreatment with PCl₅ to produce free amines 4a, 4b, and 4 c respectively.These were converted to the corresponding 7-oxo-3-cephems andsubsequently to the 7-(2′-pyridylmethylidene)-3-cephems 5a, 5b, and 5c.These were readily oxidized to the corresponding sulfones upon treatmentwith excess mCPBA and the 4-position carboxylate deprotected bytreatment with TFA (followed by neutralization with bicarbonate) toproduce the corresponding sodium salts 7a, 7b, and 7c.

Iodide 6 c was also useful in producing other C3 substituted analogsthrough Stille Coupling reactions with selected organostannanes as shownin FIG. 2. Such reactions resulted in the production of representativeC3-sulfides, aryl, and heteroaryl compounds which were also deprotectedas shown in FIG. 2. The C3 sufides 8a and 8b could also be oxidized tothe corresponding C3 sulfonyl compounds and deprotected to produce thecorresponding sodium salts as shown in FIG. 3.

Additionally, compound 6 c was converted to the C3 stannylated analog asshown in FIG. 4. This compound was utilized to generate the C3fluorinated (14a) and C3 unsubstituted (14b) compounds as shown.

Using procedures similar to those described herein, as well as standardsynthetic techniques, the compounds of formula (I) can be prepared.

Pharmaceutically acceptable salts of compounds of formula (I) wherein R₄has been replaced with a pharmaceutically acceptable cation (e.g. asodium or potassium ion) can conveniently be prepared from acorresponding compound of formula (I) wherein R₄ is hydrogen, byreaction with a suitable base.

A useful intermediate for preparing a compound of formula (I), whereinR₄ is hydrogen, is a corresponding compound wherein R₄ has been replacedwith a suitable removable carboxy protecting group. Such protectinggroups are well known in the art, for example, see Greene, T. W.; Wutz,P. G. M. “Protecting Groups In Organic Synthesis” second edition, 1991,New York, John Wiley & Sons, Inc. Preferred protecting groups include(C₁-C₁₀)alkyl, (C₂-C₁₀)alkenyl, (C₃-C₈)cycloalkyl, (C₂-C₁₀)alkynyl,aryl, benzyl, or benzhydryl. Thus the invention provides compounds offormula (I) wherein R₁, R₂, and R₃ have any of the values, specificvalues, or preferred values defined herein, and wherein R₄ is(C₁-C₁₀)alkyl, (C₂-C₁₀)alkenyl, (C₃-C₈)cycloalkyl, (C₂-C₁₀)alkynyl,aryl, benzyl, and benzhydryl.

Another useful intermediate for preparing a compound of formula (I), isa compound of formula (I) wherein R₃ is a tin containing group, e.g., agroup of formula —Sn(R)₃ wherein each R is (C₁-C₆)alkyl. Accordingly,the invention also provides a compound of formula (I) wherein R₁, R₂,and R₄ have any of the values described herein, and wherein R₃ is—Sn(R)₃ wherein each R is (C₁-C₆)alkyl.

A compound of formula (I) wherein A is sulfonyl (—SO₂—) can be preparedby oxidation of a corresponding compound of formula (I) wherein A isthio (—S—), for example, by using meta-chloroperbenzoic acid (mCPBA).

A compound of formula (I) wherein A is sulfinyl (—SO—) can be preparedby oxidation of a corresponding compound of formula (I) wherein A isthio (—S—), using one equivalent of an acceptable oxidizing agent, forexample, mCPBA. A compound of formula (I) wherein R₃ is hydrogen, aryl,heteroaryl, or —SR_(h), can be prepared by combining a correspondingcompound of formula (I) wherein R₃ is halo, with an organostannane offormula (R_(a))₃Sn—R₃ and a catalyst, to provide the compound of formula(I). Accordingly, the invention also provides a method of preparing acompound of formula (I) wherein R₃ is hydrogen, aryl, heteroaryl, or—SR_(h), and R₄ is hydrogen; comprising: combining a correspondingcompound of formula (I) wherein R₃ is halo and R₄ is a protecting group,with an organostannane of formula (R_(a))₃Sn—R₃ and a catalyst, toprovide a compound of formula (I) wherein R₃ is hydrogen, aryl,heteroaryl, or —SR_(h),; and R₄ is a protecting group, and removing theprotecting group R₄ to provide the compound of formula (I) wherein R₃ ishydrogen, aryl, heteroaryl, or —SR_(h), and R₄ is hydrogen. In oneembodiment, the catalyst comprises palladium (e.g. Pd₂(dba)₂). Inanother embodiment R_(a) is methyl, ethyl, propyl, or butyl.

The invention also provides a method of preparing a compound of formula(I) wherein R₃ is aryl, heteroaryl, or —CH═CHC(═O)NR_(m)R_(p), and R₄ ishydrogen; comprising: combining a corresponding compound of formula (I)wherein R₃ is —Sn(R)₃, each R is (C₁-C₆)alkyl, and R₄ is a protectinggroup, with the requsite organohalide or organotriflate (e.g. a compoundof formula R₃—X wherein X is a halogen ot triflate) and a catalyst, toprovide a compound of formula (I) wherein R₃ is aryl, heteroaryl, or—CH═CHC(═O)NR_(m)R_(p); and R₄ is a protecting group, and removing theprotecting group R₄ to provide the compound of formula (I) wherein R₃ isaryl, heteroaryl, or —CH═CHC(═O)NR_(m)R_(p), and R₄ is hydrogen. In oneembodiment, each R is methyl, ethyl, propyl, or butyl.

The invention also provides a method of preparing a compound of formula(I) wherein R₃ is H or F, and R₄ is hydrogen; comprising: combining acorresponding compound of formula (I) wherein R₃ is —Sn(R)₃, each R is(C₁-C₆)alkyl, and R₄ is a protecting group, with AgOTf and XeF₂ toprovide a compound of formula (I) wherein R₃ is H or F; and R₄ is aprotecting group, and removing the protecting group R₄ to provide thecompound of formula (I) wherein R₃ is is H or F, and R₄ is hydrogen. Inone embodiment, each R is methyl, ethyl, propyl, or butyl.

Many of the starting materials employed in the synthetic methodsdescribed above are commercially available or are reported in thescientific literature. It may be desirable to optionally use aprotecting group during all or portions of the above described syntheticprocedures. Such protecting groups and methods for their introductionand removal are well known in the art. See Greene, T. W.; Wutz, P. G. M.“Protecting Groups In Organic Synthesis” second edition, 1991, New York,John Wiley & Sons, Inc.

In cases where compounds are sufficiently basic or acidic to form stablenontoxic acid or base salts, administration of the compounds as saltsmay be appropriate. Examples of pharmaceutically acceptable salts areorganic acid addition salts formed with acids which form a physiologicalacceptable anion, for example, tosylate, methanesulfonate, acetate,citrate, malonate, tartarate, succinate, benzoate, ascorbate,α-ketoglutarate, and α-glycerophosphate. Suitable inorganic salts mayalso be formed, including hydrochloride, sulfate, nitrate, bicarbonate,and carbonate salts.

Pharmaceutically acceptable salts may be obtained using standardprocedures well known in the art, for example, by reacting asufficiently basic compound such as an amine with a suitable acidaffording a physiologically acceptable anion. Alkali metal (for example,sodium, potassium or lithium) or alkaline earth metal (for example,calcium) salts of carboxylic acids can also be made.

The compounds of formula (I) can be formulated as pharmaceuticalcompositions and administered to a mammalian host, such as a humanpatient in a variety of forms adapted to a selected route ofadministration, i.e., by oral, parenteral, intravenous, intramuscular,topical, or subcutaneous routes.

Thus, the present compounds may be systemically administered, e.g.,orally, in combination with a pharmaceutically acceptable vehicle suchas an inert diluent or an assimilable edible carrier. They may beenclosed in hard or soft shell gelatin capsules, may be compressed intotablets, or may be incorporated directly with the food of the patient'sdiet. For oral therapeutic administration, the active compound may becombined with one or more excipients and used in the form of ingestibletablets, buccal tablets, troches, capsules, elixirs, suspensions,syrups, wafers, and the like. Such compositions and preparations shouldcontain at least 0.1% of active compound. The percentage of thecompositions and preparations may, of course, be varied and mayconveniently be between about 2 to about 60% of the weight of a givenunit dosage form. The amount of active compound in such therapeuticallyuseful compositions is such that an effective dosage level will beobtained.

The tablets, troches, pills, capsules, and the like may also contain thefollowing: binders such as gum tragacanth, acacia, corn starch orgelatin; excipients such as dicalcium phosphate; a disintegrating agentsuch as corn starch, potato starch, alginic acid and the like; alubricant such as magnesium stearate; and a sweetening agent such assucrose, fructose, lactose or aspartame or a flavoring agent such aspeppermint, oil of wintergreen, or cherry flavoring may be added. Whenthe unit dosage form is a capsule, it may contain, in addition tomaterials of the above type, a liquid carrier, such as a vegetable oilor a polyethylene glycol. Various other materials may be present ascoatings or to otherwise modify the physical form of the solid unitdosage form. For instance, tablets, pills, or capsules may be coatedwith gelatin, wax, shellac or sugar and the like. A syrup or elixir maycontain the active compound, sucrose or fructose as a sweetening agent,methyl and propylparabens as preservatives, a dye and flavoring such ascherry or orange flavor. Of course, any material used in preparing anyunit dosage form should be pharmaceutically acceptable and substantiallynon-toxic in the amounts employed. In addition, the active compound maybe incorporated into sustained-release preparations and devices.

The active compound may also be administered intravenously orintraperitoneally by infusion or injection. Solutions of the activecompound or its salts can be prepared in water, optionally mixed with anontoxic surfactant. Dispersions can also be prepared in glycerol,liquid polyethylene glycols, triacetin, and mixtures thereof and inoils. Under ordinary conditions of storage and use, these preparationscontain a preservative to prevent the growth of microorganisms.

The pharmaceutical dosage forms suitable for injection or infusion caninclude sterile aqueous solutions or dispersions or sterile powderscomprising the active ingredient which are adapted for theextemporaneous preparation of sterile injectable or infusible solutionsor dispersions, optionally encapsulated in liposomes. In all cases, theultimate dosage form should be sterile, fluid and stable under theconditions of manufacture and storage. The liquid carrier or vehicle canbe a solvent or liquid dispersion medium comprising, for example, water,ethanol, a polyol (for example, glycerol, propylene glycol, liquidpolyethylene glycols, and the like), vegetable oils, nontoxic glycerylesters, and suitable mixtures thereof. The proper fluidity can bemaintained, for example, by the formation of liposomes, by themaintenance of the required particle size in the case of dispersions orby the use of surfactants. The prevention of the action ofmicroorganisms can be brought about by various antibacterial andantifungal agents, for example, parabens, chlorobutanol, phenol, sorbicacid, thimerosal, and the like. In many cases, it will be preferable toinclude isotonic agents, for example, sugars, buffers or sodiumchloride. Prolonged absorption of the injectable compositions can bebrought about by the use in the compositions of agents delayingabsorption, for example, aluminum monostearate and gelatin.

Sterile injectable solutions are prepared by incorporating the activecompound in the required amount in the appropriate solvent with variousof the other ingredients enumerated above, as required, followed byfilter sterilization. In the case of sterile powders for the preparationof sterile injectable solutions, the preferred methods of preparationare vacuum drying and the freeze drying techniques, which yield a powderof the active ingredient plus any additional desired ingredient presentin the previously sterile-filtered solutions.

For topical administration, the present compounds may be applied in pureform, i.e., when they are liquids. However, it will generally bedesirable to administer them to the skin as compositions orformulations, in combination with a dermatologically acceptable carrier,which may be a solid or a liquid.

Useful solid carriers include finely divided solids such as talc, clay,microcrystalline cellulose, silica, alumina and the like. Useful liquidcarriers include water, alcohols or glycols or water-alcohol/glycolblends, in which the present compounds can be dissolved or dispersed ateffective levels, optionally with the aid of non-toxic surfactants.Adjuvants such as fragrances and additional antimicrobial agents can beadded to optimize the properties for a given use. The resultant liquidcompositions can be applied from absorbent pads, used to impregnatebandages and other dressings, or sprayed onto the affected area usingpump-type or aerosol sprayers.

Thickeners such as synthetic polymers, fatty acids, fatty acid salts andesters, fatty alcohols, modified celluloses or modified mineralmaterials can also be employed with liquid carriers to form spreadablepastes, gels, ointments, soaps, and the like, for application directlyto the skin of the user.

Examples of useful dermatological compositions which can be used todeliver the compounds of the invention to the skin are disclosed inJacquet et al. (U.S. Pat. No. 4,608,392), Geria (U.S. Pat. No.4,992,478), Smith et al. (U.S. Pat. No. 4,559,157) and Wortzman (U.S.Pat. No. 4,820,508).

The present compositions may also be prepared in suitable forms forabsorption through the mucous membranes of the nose and throat orbronchial tissues and may conveniently take the form of powder or liquidsprays or inhalants, lozenges, throat paints, etc. For medication of theeyes or ears, the preparations may be presented as individual capsules,in liquid or semi-solid form, or may be used as drops, etc. Topicalapplications may be formulated in hydrophobic or hydrophilic bases asointments, creams, lotions, paints, powders, etc.

For veterinary medicine, the composition may, for example, be formulatedas an intramammary preparation in either long acting or quick-releasebases.

Useful dosages of the compounds of the invention can be determined bycomparing their in vitro activity, and in vivo activity in animalmodels. Methods for the extrapolation of effective dosages in mice, andother animals, to humans are known to the art; for example, see U.S.Pat. No. 4,938,949.

Generally, the concentration of the compound(s) of the invention in aliquid composition, such as a lotion, will be from about 0.1-25 wt-%,preferably from about 0.5-10 wt-%. The concentration in a semi-solid orsolid composition such as a gel or a powder will be about 0.1-5 wt-%,preferably about 0.5-2.5 wt-%.

The compositions per unit dosage, whether liquid or solid may containfrom 0.1% to 99% of active material (the present 7-vinylidenecephalosporins and optional antibiotic), the preferred range being fromabout 10-60%. The composition will generally contain from about 15 mg toabout 1500 mg by weight of active ingredient based upon the total weightof the composition; however, in general, it is preferable to employ adosage amount in the range of from about 250 mg to 1000 mg. Inparenteral administration the unit dosage is usually the pure compoundin a slightly acidified sterile water solution or in the form of asoluble powder intended for solution. Single dosages for injection,infusion or ingestion may be administered, i.e., 1-3 times daily, toyield levels of about 0.5-50 mg/kg, for adults.

The invention provides a pharmaceutical composition, comprising aneffective amount of a compound of formula (I) as described hereinabove;or a pharmaceutically acceptable salt thereof; and a pharmaceuticallyacceptable carrier. The invention also provides a pharmaceuticalcomposition comprising an effective amount of a compound of formula (I)as described hereinabove; or a pharmaceutically acceptable salt thereof;a β-lactam antibiotic; and a pharmaceutically acceptable carrier. Thepresent compositions are preferably presented in a form suitable forabsorption by the gastro-intestinal tract.

Any β-lactam antibiotic is suitable for use in the pharmaceuticalcomposition of the invention. β-lactam antibiotics which are well knownin the art include those disclosed by R. B. Morin and M. Gorin, M. Eds.;Academic Press, New York, 1982; vol. 1-3. Preferred β-lactamantibiotics, suitable for use in the pharmaceutical composition of theinvention, include β-lactam antibiotics which are preferentiallydeactivated by Class A and Class C β-lactamase enzymes, for example,amoxicillin, piperacillin, ampicillin, ceftizoxime, cefotaxime,cefuroxime, cephalexin, cefaclor, cephaloridine, and ceftazidime.

The ability of a compound of the invention to function as a β-lactamaseinhibitor can be demonstrated using the test described below, or usingother tests which are well known in the art. Representative compounds offormula (I) were evaluated as inhibitors of the Class C β-lactamase ofEnterobacter cloacae P-99, a cephalosporinase, and TEM-1, a Class Apenicillinase, by relative IC₅₀ analysis. The IC₅₀ value represents theconcentration of inhibitor required to effect a 50% loss of activity offree enzyme. The IC₅₀ value of each compound was determined as follows.Following a 10 minute incubation of a dilute solution of enzyme (2.56nM) and inhibitor (<0.64 mM), a 50 mL aliquot of this incubation mixturewas then further diluted into 1 mL nitrocefin solution, and the rate ofhydrolysis was measured during a 1 minute period by monitoring theabsorbance of nitrocefin as a function of time. In addition, the IC₅₀values of tazobactam were determined as relative controls. The data ispresented in Table 1 below for representative compounds of the formulaeI. TABLE 1 beta-Lactamase inhibitory activity against representativeclass A (TEM-1) and class C (P99) enzymes TEM-1 P99 Compound (IC₅₀, μm)(IC₅₀, μm)  7a 1.82 0.003  7b 0.791 0.0029  7c 1.28 0.0047  9a 1.0650.059  9b 0.012 0.0217  9c 3.54 0.043  9d 9.14 0.038 11a 0.0076 0.090711b 0.0094 0.174 14a 1.84 0.011 14b 18.52 0.116 18a 0.240 0.824 18b 7.690.128 21a 0.39 1.1 21b 1.59 4.2 21c 0.053 6.34 tazobactam 0.25 101.6

The present β-lactamase inhibitors of formula (I) are particularlyuseful in the treatment of infections associated with Enterobacter,Citrobacter, and Serratia. These bacteria have the ability to attach tothe epithelial cells of the bladder or kidney (causing urinary tractinfections) and are resistant to multiple antibiotics includingamoxicillin and 10 ampicillin.

The present β-lactamase inhibitors of formula (I) are also be useful inthe treatment of infections associated with highly resistantPneumococci. Such diseases include otitis media, sinusitis, meningitis(both in children and adults), bacteremia, and septic arthritis.Resistant pneumococcal strains have surfaced in many parts of the world.For example, in Hungary, 58% of S. pneumoniae are resistant topenicillin, and 70% of children who are colonized with S. pneumoniaecarry resistant strains that are also resistant to tetracycline,erythromycin, trimethoprin/sulfamethoxazole (TMP/SMX), and 30% resistantto chloramphenicol. Klebsiella pneumoniae (resistant via the productionof β-lactamase) have caused hospital outbreaks of wound infection andsepticemia.

Other features of the invention will become apparent in the course ofthe following descriptions of exemplary embodiments which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLES 1-3 (FIG. 1)

Preparation of Compound 2

Diphenylmethyl7-phenylacetamido-3-(trifluorosulfonyloxy)-3-cephem-4-carboxylate (2).This compound and the subsequent halides were prepared according to themethod of Farina (Farina et. al. J. Org. Chem. 54, 4962-4966 (1989)). Asolution of benzhydryl 3-hydroxy-7-(phenylacetamido)ceph-3-em (1, 41 g,84 mmol, commercially available from Otsuka Chemical Corp.) in anhydrousCH₂Cl₂ (600 mL) was cooled to −78° C. and treated with drydiisopropylethylamine (15.6 mL, 90 mmol) and trifluoromethanesulfonicanhydride (14.3 mL, 85 mmol). The mixture was then stirred at −78° C.for 20 min. The solution was then diluted with an addition 1 L of dryCH₂Cl₂ and the cooling bath was removed. The organic phase was washedwith water (2×1 L) and brine (1×500 mL). Then it was dried over Na₂SO₄and concentrated to afford the desired triflate (2) as an off-whiteamorphous powder. Yield=43.5 g (85%). ¹H NMR (CDCl₃, 400 MHz) δ=3.42 (d,J=18 Hz, 1H), 3.70-3.63 (m, 2H), 3.75 (d, J=18 Hz, 1H), 5.03 (d, J=5 Hz,1H), 5.91-5.87 (m, 1H), 6.02 (d, J=8.7 Hz, 1H), 6.98 (s, 1H), 7.51-7.24(m, 15H).

Preparation of Compounds 3a-3c

General Procedure for the synthesis of diphenylmethyl3-halo-7-(phenylacetamido)-3-cephem-4-carboxylates (3a, 3b, and 3c ).

To a solution of triflate 2 (10 mmol) in anhydrous THF (100 mL) wasadded fresh anhydrous LiX (25 mmol) and the reaction was allowed to stirunder argon for 24 to 36 h while monitoring the progress by ¹H NMR. Whenthe reaction was complete, water (200 mL) and EtOAc (200 mL) were addedand the organic phase was washed with water (2×100 mL), followed bybrine (1×100 mL) and dried over Na₂SO₄. Evaporation of the solventproduced the crude 3-halo-3-cephem-4-carboxylate ester which was furtherpurified by column chromatography on silica gel.

Diphenylmethyl 3-chloro-7-(phenylacetamido)-3-cephem-4-carboxylate (3a).Yield=90%. ¹H NMR (CDCl₃, 400 MHz) δ=3.43 (d, J=18.5 Hz, 1H), 3.64-3.57(m, 2H), 3.74 (d, J=18.5 Hz, 1H), 4.99 (d, J=5 Hz, 1H), 5.84-5.81 (m,1H), 6.24 (d, J=9 Hz, 1H), 6.97 (s, 1H), 7.39-7.24 (m, 15H).

Diphenylmethyl 3-bromo-7-(phenylacetamido)-3-cephem-4-carboxylate (3b).Yield=88%. ¹H NMR (CDCl₃, 400 MHz) δ=3.64-3.56 (m, 3H), 3.83 (d, J=18Hz, 1H), 5.02 (d, J=5 Hz, 1H), 5.81-5.78 (m, 1H), 6.21 (d, J=9 Hz, 1H),6.97 (s, 1H), 7.41-7.25 (m, 15H).

Diphenylmethyl 3-iodo-7-(phenylacetamido)-3-cephem-4-carboxylate (3c ).Yield=72%. ¹H NMR (CDCl₃, 400 MHz) δ=3.67-3.56 (m, 2H), 3.70 (d, J=18.5Hz, 1H), 3.84 (d, J=18.5 Hz, 1H), 5.04 (d, J=5 Hz, 1H), 5.85-5.81 (m,1H), 6.16 (d, J=9 Hz, 1H), 6.96 (s, 1H), 7.41-7.24 (m, 15H).

Preparation of Compounds 4a-4 c

General procedure for the synthesis of diphenylmethyl3-halo-7-amino-3-cephem-4-carboxylates (4a, 4b, and 4 c ).

To a cooled (0° C.) solution of PCl₅ (25 mmol) in dry CH₂Cl₂ was addeddry pyridine (25 mmol) slowly while cooling the reaction with an icebath. The reaction was allowed to stir at this temperature for 1 h. Theappropriate phenylacetamido-3-cephem-4-carboxylate (3a, 3b, or 3c ) wasthen added in one portion and the reaction allowed to continue stirringfor 1.5 h at the same temperature. The reaction mixture was then cooledto −78° C. and MeOH (30 mL) was added slowly and the reaction stirredfor an additional 1 h. The reaction mixture was then allowed to slowlywarm to reach a temperature between −10 and 0° C. Water (30 mL) was thenadded and the solution was concentrated under vacuum to remove CH₂Cl₂and most of the MeOH. To the remaining residue, EtOAc (150 mL) and water(100 mL) were added and the water layer was basified by the addition ofNaHCO₃. The organic layer was then separated and the aqueous layer wasfurther extracted with EtOAc (1×50 mL). The combined organic layer waswashed with water (1×100 mL) followed by brine (1×100 mL). The organiclayer was then dried over Na₂SO₄ and concentrated under vacuum. Thecrude product was further purified by column chromatography using amixture of EtOAc and CH₂Cl₂ as eluent.

Diphenylmethyl 3-chloro-7-amino-3-cephem-4-carboxylate (4a). Yield=74%.¹H NMR (CDCl₃, 400 MHz) δ=1.74 (br s, 2H), 3.48 (d, J=18.5 Hz, 1H), 3.8(d, J=18.5 Hz, 1H), 4.75 (d, J=5.0 Hz, 1H), 4.98 (d, J=5.0 Hz, 1H), 7.00(s, 1H), 7.57-7.26 (m, 10H).

Diphenylmethyl 3-bromo-7-amino-3-cephem-4-carboxylate (4b). Yield=72%.¹H NMR (CDCl₃, 400 MHz) δ=1.74 (br s, 2H), 3.62 (d, J=18 Hz, 1H), 3.88(d, J=18 Hz, 1H), 4.75 (d, J=5.0 Hz, 1H), 5.00 (d, J=5.0 Hz, 1H), 7.00(s, 1H), 7.44-7.25 (m, 10H).

Diphenylmethyl 3-iodo-7-amino-3-cephem-4-carboxylate (4 c ). Yield=76%.¹H NMR (CDCl₃, 400 MHz) δ=1.75 (br s, 2H), 3.76 (d, J=18.5 Hz, 1H), 3.90(d, J=18.5 Hz, 1H), 4.75 (d, J=5 Hz, 1H), 5.04 (d, J=5.0 Hz, 1H), 7.00(s, 1H), 7.46-7.26 (m, 10H).

Preparation of Compounds 5a-5c

General procedure for synthesis of diphenylmethyl3-halo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylates (5a, 5b, and5c) from amines (4a, 4b, and 4c ).

To a solution of triphenyl(2-pyridylmethyl)phosphonium chloridehydrochloride (20 mmol, Aldrich Chemical Co.) in anhydrous THF (150 mL)was added potassium tert-butoxide (15 mmol). This slurry was thenstirred at room temperature for 2 h to generate the Wittig Reagent.

Separately, to a solution of amine (4, 20 mmol) in EtOAc (200 mL) wereadded catalytic trifluoroacetic acid (200 μL) and isopropylnitrite (asolution 30 to 50% in CH₂Cl₂, prepared by the method of Blacklock et.al., J. Org. Chem., 54, 3907-3913 (1989)). After completion of thereaction (approx. 5 min, monitored by TLC), EtOAc was removed undervacuum and the resultant 7-diazo-3-cephem-4-carboxylates was driedcompletely under high vacuum. This diazo compound was then immediatelydissolved in anhydrous benzene (200 mL) and propylene oxide (25 mL), andtreated with a catalytic amount of rhodium octanoate (0.5 g). Thereaction was observed to evolve gas. After the completion of such gasevolution, the benzene solvent was removed under vacuum and theremaining solid (7-oxo-3-cephem-4-carboxylate) dissolved in dry CH₂Cl₂(200 mL). This solution was then cooled to −78° C.

The solution of the aforementioned Wittig Reagent was then slowly added(via cannula) to this cold (−78° C.) solution of ketone and the reactionstirred at this temperature for 30 min. Then a saturated aqueoussolution of NH₄Cl was added and the reaction mixture slowly warmed toroom temperature with stirring. The layers were separated and theaqueous layer extracted with an additional portion of CH₂Cl₂. Thecombined organic layers were washed with water (1×100 mL), brine (1×100mL), and dried over Na₂SO₄. The crude product was purified by columnchromatography (silica gel) using a mixture of EtOAc and CH₂Cl₂ aseluent.

Diphenylmethyl 3-chloro-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylate(5a). Overall yield (three steps from 4a)=35%. ¹H NMR (CDCl₃, 400 MHz)δ=3.54 (d, J=18.5 Hz, 1H), 3.96 (d, J=18.5 Hz, 1H), 5.71 (s, 1H), 7.03(s, 1H), 7.41-7.28 (m, 13H), 7.76 (t of d, J=1.6 Hz and 7.7 Hz, 1H),8.76 (d, J=4 Hz, 1H).

Diphenylmethyl 3-bromo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylate(5b). Overall yield (three steps from 4b)=35/%. ¹H NMR (CDCl₃, 400 MHz)δ=3.59 (d, J=18.5 Hz, 1H), 3.95 (d, J=18.5 Hz, 1H), 5.73 (d, J=1 Hz,1H), 7.05 (s, 1H), 7.47-7.26 (m, 13H), 7.77 (t of d, J=1.6 Hz and 7.7Hz, 1H), 8.76 (d, J=4 Hz, 1H).

Diphenylmethyl 3-iodo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylate(5c). Overall yield (three steps from 4a)=33%. ¹H NMR (CDCl₃, 400 MHz)δ=3.70 (d, J=18.5 Hz, 1H), 3.94 (d, J=18.5 Hz, 1H), 5.76 (s, 1H), 7.06(s, 1H), 7.42-7.26 (m, 13H), 7.73 (t of d, J=1.6 and 7.7 Hz, 1H), 8.71(d, J=4.0 Hz, 1 H).

Preparation of Compounds 6a-6c

General procedure for formation of diphenylmethyl1,1-dioxo-3-halo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylates (6a,6b, and 6c) using oxidation with mCPBA.

To a solution of sulfide (5) in CH₂Cl₂ (15 mL) was added mCPBA (2.5mmol) and the reaction was stirred for 20 min at rt. A saturated aqueoussolution of Na₂SO₃ was then added and the layers were separated. Theorganic layer was washed with aqueous NaHCO₃ (1×25 mL), water (1×25 mL),and brine (1×25 mL). The organic layer was then dried over Na₂SO₄,concentrated and the crude product further purified by flash columnchromatography (silica gel) using a mixture of EtOAc and CH₂Cl₂ aseluent.

Diphenylmethyl3-chloro-1,1-dioxo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylate(6a). Yield=72%. ¹H NMR (CDCl₃, 400 MHz) δ=4.04 (d, J=18 Hz, 1H), 4.23(d, J=18 Hz, 1H), 5.93 (s, 1H), 7.03 (s, 1H), 7.39-7.31 (m, 13H), 7.73(t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.66 (d, J=4 Hz, 1H).

Diphenylmethyl3-bromo-1,1-dioxo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylate (6b).Yield=75%. ¹H NMR (CDCl₃, 400 MHz) δ=4.10 (d, J=18 Hz, 1H), 4.34 (d oft, J=18 Hz, 1H), 5.95 (s, 1H), 7.04 (s, 1H), 7.47-7.3 (m, 13H), 7.73 (tof d, J=1.6 Hz and 7.7 Hz, 1H), 8.67 (d, J=4 Hz, 1H).

Diphenylmethyl3-iodo-1,1-dioxo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylate (6c).Yield=78%. ¹H NMR (CDCl₃, 400 MHz) δ=8.66 (d, J=4.0 Hz, 1H), 7.71 (t ofd, J=1.6 and 7.7 Hz, 1H), 7.49-7.25 (m, 13H), 7.03 (s, 1H), 5.96 (s,1H), 4.38 (d, J=18 Hz, 1H), 4.18 (d, J=18 Hz, 1H). ¹³C NMR (CDCl₃, 400MHz) δ=160.3, 160.2, 150.4, 150.2, 138.9, 138.6, 137.0, 132.7, 130.9,128.6, 128.5, 128.4, 128.2, 128.0, 127.5, 127.2, 126.6, 126.4, 125.3,80.5, 74.1, 64.2. HRMS calcd for C₂₆H₁₉IN₂O₅S [M+H]⁺599.0138, obsd599.0135.

Preparation of Compounds 7a-7c

General Procedure for the deprotection of benzhydryl esters.

A solution of the appropriate benzhydryl ester (0.1 mmol) in dry anisole(3.0 mmol) was cooled in an ice-salt bath and trifluoroacetic acid (12.0mmol) was added slowly via syringe under argon atmosphere. After 20minutes, the volatile components were removed under vacuum and theresidue was dissolved in EtOAc (5 mL). The EtOAc layer was extractedwith aqueous NaHCO₃ (2×0.15 mmol in 4 mL H₂O). The combined water layerswere directly loaded onto a chromatography column (high porous polymer,MCI gel, CHP20P Mitsubishi Chemical Corp., White Plains N.Y., approx. 75to 150 mL of resin) and the product eluted with 5% EtOH in deionizedwater. The yield was typically between 60 to 80%.

Example 1

Sodium3-chloro-1,1-dioxo-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(7a). Prepared from ester 7a according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=6.28 (s, 1H), 7.44-7.34 (m, 1H), 7.48 (s, 1H), 7.62-7.59 (m,1H), 7.84 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.55 (d, J=4.0 Hz, 1H).

Example 2

Sodium3-bromo-1,1-dioxo-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate (7b).Prepared from ester 7b according to the general procedure describedabove for the deprotection of benzhydryl esters. ¹H NMR (D₂O, 400 MHz)δ=6.29 (s, 1H), 7.45-7.35 (m, 1H), 7.49 (s, 1H), 7.6-7.57 (m, 1H), 7.85(t of d, J=1.6 and 7.7 Hz, 1H), 8.56 (d, J=4.0 Hz, 1H).

Example 3

Sodium 1,1-dioxo-3-iodo-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(7c). Prepared from ester 7c according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=6.29 (d, J=1 Hz, 1H), 7.33-7.30 (m, 1H), 7.45 (d, J=1 Hz,1H), 7.65-7.61 (m, 1H), 7.83 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.54 (d,J=4.0 Hz, 1H).

EXAMPLES 4-7 (FIG. 2)

Preparation of Compounds 8a-8d

General procedure for the Stille Couplings of iodide 6 c withorganostannanes to produce compounds 8a-8d.

To a solution of 6 c (72 mg, 0.12 mmol) in anhydrous THF were added theappropriate organostannane (0.11 mmol, e.g., Bu₃Sn—R₃) and Pd₂(dba)₃ (5mg, 0.011 mmol) under an Ar atmosphere. The reaction mixture was stirredat 65° C. for 2.5 h and was monitored by ¹H NMR. After completion of thereaction, solvent was removed under reduced pressure and the productdissolved in CH₂Cl₂. The solution was then washed with water (10 mL) andbrine (10 mL). The organic layer was concentrated and purified by columnchromatogrphy (silica gel).

Diphenylmethyl1,1-dioxo-3-methylsulfanyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(8a). Yield=67%. ¹H NMR (CDCl₃, 400 MHz) δ=2.35 (s, 3H), 3.98 (d, J=15.5Hz, 1H), 4.18 (d, J=15.5 Hz, 1H), 5.72 (d, J=1 Hz, 1H), 6.97 (s, 1H),7.4-7.26 (m, 13H), 7.71 (t of d, J=1.6 and 7.7 Hz, 1H), 8.66 (d, J=4 Hz,1H).

Diphenylmethyl1,1-dioxo-3-phenylsulfanyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(8b). Yield=72%. ¹H NMR (CDCl₃, 400 MHz) δ=8.63 (d, J=3.9 Hz, 1H), 7.71(t of d, J=1.6 and 7.7 Hz, 1H), 7.53-7.26 (m, 19H), 7.02 (s, 1H), 5.75(s, 1H), 3.75 (d, J=15.6 Hz, 1H), 3.59 (d, J=15.6 Hz, 1H).

Diphenylmethyl1,1-dioxo-7-(2′-pyridylmethylidine)-3-(thiophen-2′-yl)-3-cephem-4-carboxylate(8c). Yield=78%. ¹H NMR (CDCl₃, 400 MHz) δ=8.69 (d, J=4.0 Hz, 1H), 7.72(t of d, J=1.6 and 7.7 Hz, 1H), 7.4-7.21 (m, 12H), 7.07-7.05 (m, 2H),(m, 2H), 6.96 (s, 1H), 6.84 (dd, J=1 and 4 Hz, 1H), 6.75 (t, J=4 Hz,1H), 5.96 (s, 1H), 4.17 (d, J=18 Hz, 1H), 4.08 (d, J=18 Hz, 1H).

Diphenylmethyl1,1-dioxo-3-phenyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(8d). Yield=56%. ¹H NMR (CDCl₃, 400 MHz) δ=8.65 (d, J=3.9 Hz, 1H), 7.7(t of d, J=1.6 and 7.7 Hz, 1H), 7.34-7.13 (m, 16H), 6.92 (d, J=6.7 Hz,2H), 6.85 (s, 1H), 5.98 (s, 1H), 4.08 (s, 2H). ¹³C NMR (CDCl₃, 400 MHz)δ=160.8, 159.2, 150.2, 150.0, 138.6, 138.1, 136.5, 134.9, 132.8, 129.9,128.9, 128.5, 128.09, 127.9, 127.7, 127.5, 127.2, 127.0, 126.9, 125.9,124.7, 79.0, 73.0, 56.7.

Preparation of Compounds 9a-9d

Compounds 9a-9d were prepared from Compounds 8a-8d using the GeneralProcedure for the Deprotection of benzhydryl esters described above.

Example 4

Sodium1,1-dioxo-3-methylsulfanyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(9a). Prepared from ester 8a according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=2.2 (s, 3H), 6.17 (s, 1H), 7.42-7.36 (m, 2H), 7.43 (s, 1H),7.61-7.58 (m, 1H), 7.81 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.52 (d,J=4.0 Hz, 1H).

Example 5

Sodium1,1-dioxo-3-phenylsulfanyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(9b). Prepared from ester 8b according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=6.32 (d, J=1 Hz, 1H), 7.42-7.33 (m, 6H), 7.46 (s, 1H),7.6-7.58 (m, 1H), 7.81 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.51 (d, J=4.0Hz, 1H).

Example 6

Sodium 1,1-dioxo-7-(2 ′-pyridylmethylidine)-3-(thiophen-2′-yl)-3-cephem-4-carboxylate (9c). Prepared from ester 8c according tothe general procedure described above for the deprotection of benzhydrylesters. ¹H NMR (D₂O, 400 MHz) δ=6.23 (s, 1H), 7.03-7.00 (m, 1H), 7.1 (d,J=4 Hz, 1H), 7.42-7.4 (m, 2H), 7.45 (s, 1H), 7.61 (d, J=7.6 Hz, 1H),7.83 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.54 (d, J=4.0 Hz, 1H).

Example 7

Sodium1,1-dioxo-3-phenyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(9d). Prepared from ester 8d according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=6.24 (s, 1H), 7.39-7.28 (m, 6H), 7.45 (s, 1H), 7.62-7.60 (m,1H), 7.82 (t of d, J=1.6 Hz and 7.6 Hz, 1H), 8.54 (d, J=4.0 Hz, 1H).

EXAMPLES 8 and 9 (FIG. 3)

Preparation of Compounds 10a and 10b

General procedure for oxidation of the 3-position sulfur of compounds 8aand 8b to produce the corresponding 3-position sulfones (10a and 10b).

To a solution of sulfide (8a or 8b, 0.1 mmol) in CH₂Cl₂ (5 mL) was addedmCPBA (0.4 mmol) and the reaction mixture stirred at room temperatureuntil the reaction was complete (monitored by TLC, approx. 8 h). Thereaction was then quenched by the addition of a saturated solution ofNaHSO₃. The layers were separated and the aqueous layer extracted withan addition portion of CH₂Cl₂ (1×20 mL). The combined organic layerswere washed with NaHCO₃ (1×20 mL), water (1×20 mL), and brine (1×20 mL).The organic layer was then dried over Na₂SO₄, concentrated under vacuum,and purified by flash chromatography (silica gel).

Diphenylmethyl1,1-dioxo-3-methylsulfonyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(10a). Yield=81%. ¹H NMR (CDCl₃, 400 MHz) δ=2.81 (s, 3H), 3.84 (d,J=18.5 Hz, 1H), 4.34 (d, J=18.5 Hz, 1H), 6.08 (s, 1H), 7.03 (s, 1H),7.43-7.3 (m, 13H), 7.74 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.69 (d, J=4Hz, 1H).

Diphenylmethyl1,1-dioxo-3-phenylsulfonyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(10b). Yield=75%. ¹H NMR (CDCl₃, 400 MHz) δ=3.48 (d, J=18 Hz, 1H), 4.16(d, J=18 Hz, 1H), 5.94 (s, 1H), 7.05 (s, 1H), 7.44-7.19 (m, 17H),7.75-7.71 (m, 2H), 8.61 (d, J=4 Hz, 1H).

Preparation of Compounds 11a and 11b

Compounds 11a and 11b were prepared from Compounds 10a and 10b using theGeneral Procedure for the Deprotection of benzhydryl esters describedabove.

Example 8

Sodium1,1-dioxo-3-methylsulfonyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(11a). Prepared from ester 10a according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=3.2 (s, 3H), 4.53 (d, J=17.6 Hz, 1H), 4.32 (d, J=17.6 Hz,1H), 6.41 (s, 1H), 7.49-7.40 (m, 1H), 7.66-7.58 (m, 2H), 7.86 (t of d,J=1.6 and 7.6 Hz, 1H), 8.60 (d, J=4.0 Hz, 1H).

Example 9

Sodium1,1-dioxo-3-phenylsulfonyl-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(11b). Prepared from ester 10b according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=6.33 (s, 1H), 7.40-7.39 (m, 1H), 7.62-7.54 (m, 6H), 7.71 (m,1H), 7.83 (t of d, J=1.6 and 7.6 Hz, 1H), 8.55 (d, J=4.0 Hz, 1H).

EXAMPLES 10 and 11 (FIG. 4)

Preparation of Compounds 12

Diphenylmethyl1,1-dioxo-7-(2′-pyridylmethylidine)-3-(trimethylstannyl)-3-cephem-4-carboxylate(12).

To a solution of 6 c (1.0 g, 1.71 mmol) in dry THF was addedhexamethylditin (0.67 g, 2.0 mmol), Pd₂(dba)₃ (175 mg, 0.2 mmol) underan Ar atmosphere. The reaction mixture was stirred at 60° C. for 1.5 h,while monitoring by ¹H NMR. After completion of the reaction, solventwas removed under reduced pressure. The product was then dissolved inCH₂Cl₂ and washed with water (50 mL) and brine (30 mL). The organiclayer was dried (Na₂SO₄), concentrated under reduced pressure, andpurified by flash chromatography using EtOAc/CH₂Cl₂ as eluent to obtaina 60% yield of 13. ¹H NMR (CDCl₃, 400 MHz): δ=8.66 (d, J=3.9 Hz, 1H),7.72 (t of d, J=1.6 and 7.7 Hz, 1H), 7.54 (d, J=7.5 Hz, 2H), 7.43 to7.26 (m, 11H), 6.92 (s, 1H), 5.88 (s, 1H), 4.07 (d, J=18.5 Hz, 1H), 3.93(d, J=18.5 Hz, 1H), 0.15 (s, 9H). ¹³C NMR (CDCl₃, 400 MHz) δ=162.6,158.4, 150.8, 150.3, 142.1, 139.6, 139.2, 136.8, 133.9, 130.6, 129.8,128.6, 128.4, 128.2, 127.9, 127.5, 127.1, 126.0, 124.9, 80.3, 73.1,57.6,-6.6. HRMS calcd for C₂₉H₂₉N₂O₅SSn [M+H]⁺637.0819, obsd 637.0823.

Preparation of Compounds 13a and 13b

Reaction of 12 with XeF₂: Synthesis of diphenylmethyl1,1-dioxo-3-fluoro-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(13a) and diphenylmethyl1,1-dioxo-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate (13b).

To a solution of stannane 12 (0.1 mmol) in anhydrous CH₂Cl₂was addedAgOTf (0.11 mmol) and the reaction mixture was cooled in an ice-saltbath under argon. XeF₂ (0.11 mmol) was then added in one portion and thereaction stirred for 10 min. At this time, water was added, the layersseparated. The aqueous layer was extracted with an additional portion ofCH₂Cl₂ (1×25 mL), and the combined organic layers were washed with water(1×25 mL) and brine (1×25 mL) and dried over Na₂SO₄. After the solventwas removed under vacuum, the products were purified by flashchromatography on silica gel.

Diphenylmethyl1,1-dioxo-3-fluoro-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(13a). ¹H NMR (CDCl₃, 400 MHz) δ=8.65 (d, J=4.0 Hz, 1H), 7.71 (t of d,J=1.5 and 7.7 Hz, 1H), 7.47-7.27 (m, 13H), 7.04 (s, 1H), 5.84 (s, 1H),4.23 (d of d, J=and 20 Hz, 1H), 4.08 (d of d, J=5.4 and 20 Hz, 1H).

Diphenylmethyl1,1-dioxo-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate (13b). ¹H NMR(CDCl₃, 400 MHz) δ=8.66 (d, J=4.0 Hz, 1H), 7.76 (t of d, J=1.5 and 7.7Hz, 1H), 7.48-7.25 (m, 13H), 6.99 (s, 1H), 6.34 (d of d, J=3.5 and 2.0Hz), 5.94 (s, 1H), 4.04 (d of d, 1.5 and 17.5 Hz, 1H), 3.83 (d of d,J=5.6 and 17.5 Hz, 1H). HRMS calcd for C₂₆H₂₁N₂O₅S [M+H]⁺473.1171, obsd473.1148.

Preparation of Compounds 14a and 14b

Compounds 14a and 14b were prepared from Compounds 13a and 13b using theGeneral Procedure for the Deprotection of benzhydryl esters describedabove.

Example 10

Sodium1,1-dioxo-3-fluoro-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate(14a). Prepared from ester 13a according to the general proceduredescribed above for the deprotection of benzhydryl esters. ¹H NMR (D₂O,400 MHz) δ=6.19 (s, 1H), 7.46-7.35 (m, 2H), 7.58-7.55 (m, 1H), 7.8 (t ofd, J=1.6 Hz and 7.6 Hz, 1H), 8.52 (d, J=4.0 Hz, 1H).

Example 11

Sodium 1,1-dioxo-7-(2′-pyridylmethylidine)-3-cephem-4-carboxylate (14b).Prepared from ester 13b according to the general procedure describedabove for the deprotection of benzhydryl esters. ¹H NMR (D₂O, 400 MHz)δ=6.21 (s, 1H), 7.38-7.35 (m, 1H), 7.43 (s, 1H), 7.61-7.59 (m, 1H), 7.81(t of d, J=1.6 Hz and 7.6 Hz, 1H), 8.51 (d, J=4.0 Hz, 1H).

EXAMPLES 12-16 (FIGS. 5 and 6)

Preparation of Compounds 16a, 16b, and 20a-20c

General procedure for the formation of amides from carboxylic acids(Schemes 5 and 6). The following procedure was used to prepare compound16a and 16b from compound 15 and was also used to prepare compounds 20a,20b and 20c from compound 19.

To a solution of the carboxylic acid (0.3 mmol) in dry CH₃CN (10 mL) wasadded Et3N (0.6 mmol), the appropriate amine, RNH₂ (0.45 mmol), and BOPreagent (0.3 mmol) at room temperature. The reaction was monitored byTLC and was usually complete in 30 min. CH₃CN was then removed undervacuum. To the residue was added CH₂Cl₂ (25 mL) and water (25 mL). Afterseparation of the layers, the aqueous layer was extracted a second timewith CH₂Cl₂ (25 mL) and the combined organic layers were washed withwater (10 mL) followed by brine (25 mL). These organic layers were thendried over Na₂SO₄, concentrated under vacuum, and purified by columnchromatography. The yields of these coupling reactions were typically 50to 70%.

Preparation of Compounds 17a, 17b, and 19

General procedure used for the oxidation of sulfides 16a and 16b to thecorresponding sulfones 17a and 17b as well as for the oxidation ofsulfide 15 to sulfone 19.

This procedure is identical to the general procedure for formation ofdiphenylmethyl1,1-dioxo-3-halo-7-(2′-pyridylmethylidene)-3-cephem-4-carboxylates (6a,6b, and 6c) using oxidation with mCPBA which is described above.

Preparation of Compounds 18a, 18b, and 21a-21c

General procedure for the deprotection of the benzhydryl esters (17a,17b, 20a, 20b, and 20c) to produce the corresponding carboxylic acidsalts (18a, 18b, 21a, 21b, and 21c, respectively).

This procedure is identical to the General Procedure for thedeprotection of benzhydryl esters described above.

Example 12

Sodium3-(N-cyclopropyl-2′-carbamoylvinyl)-1,1-dioxo-7-(2″-pyridylmethylidine)-3-cephem-4-carboxylate(18a) ¹H NMR (D₂O, 400 MHz) δ=0.56-0.52 (m, 2H), 0.8-0.75 (m, 2H),2.68-2.65 (m, 1H), 4.26 (d, J=17.5 Hz, 1H), 4.39 (d, J=17.5 Hz, 1H),5.95 (d, J=15.5 Hz, 1H), 6.38 (s, 1H), 7.5-7.45 (m, 2H), 7.57 (s, 1H),7.69 (d, J=8 Hz, 1H), 7.9 (t of d, J=1.6 Hz and 7.7 Hz, 1 H), 8.63 (d,J=4 Hz, 1H).

Example 13

Sodium3-(N-hydroxy-2′-carbamoylvinyl)-1,1-dioxo-7-(2″-pyridylmethylidine)-3-cephem-4-carboxylate(18b) ¹H NMR (D₂O, 400 MHz) δ=5.88 (d, J=16 Hz, 1H), 6.33 (s, 1H), 7.33(d, J=16 Hz, 1H), 7.45-7.41 (m, 1H), 7.49 (s, 1H), 7.65 (d, J=8 Hz, 1H),7.86 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.6 (d, J=4 Hz, 1H).

Example 14

Sodium3-[2′-(hydrazinocarbonyl)vinyl)]-1,1-dioxo-7-(2″-pyridylmethylidine)-3-cephem-4-carboxylate(21a) ¹H NMR (D₂O, 400 MHz) δ=5.92 (d, J=16 Hz, 1H), 6.25 (s, 1H),7.68-7.43 (mi 3H), 7.67 (d, J=8 Hz, 1H ), 7.88 (t of d, J=1.6 Hz and 7.7Hz, 1H), 8.61 (d, J=4 Hz, 1H).

Example 15

Sodium3-{[N-(3″-aminopropyl)-2′-carbamoyl]vinyl)}-1,1-dioxo-7-(2′″-pyridylmethylidine)-3-cephem-4-carboxylate(21b) ¹H NMR (D₂O, 400 MHz) δ=1.87 (q, J=7 Hz, 2H), 2.96 (t, J=7.5 Hz,1H), 3.31 (t, J=6.5 Hz, 1H), 5.98 (d, J=16 Hz, 1H), 6.33 (s, 1H),7.48-7.40 (m, 2H), 7.52 (s, 1H), 7.64 (d, J=8 Hz, 1H), 7.85 (t of d,J=1.6 Hz and 7.7 Hz, 1H), 8.58 (d, J=4 Hz, 1H).

Example 16

Sodium3-[3′-(4″-methylpiperazin-1″-yl)-3′-oxopropenyl]-1,1-dioxo-7-(2′″-pyridlmethylidine)-3-cephem-4-carboxylate(21c) ¹H NMR (D₂O, 400 MHz) δ=2.19 (s, 3H), 2.46-2.42 (m, 4H), 3.8-3.76(m, 4H), 6.37 (d, J=16 Hz, 1H), 6.43 (s, 1H), 7.51-7.4 (m, 3H), 7.53 (s,1H), 7.66 (d, J=16 Hz, 1H), 7.86 (t of d, J=1.6 Hz and 7.7 Hz, 1H), 8.59(d, J=4 Hz, 1H).

Example 17

The following illustrate representative pharmaceutical dosage forms,containing a compound of Formula (I) (‘Compound X’), for therapeutic orprophylactic use in humans. (i) Tablet 1 mg/tablet ‘Compound X’ 100.0Lactose 77.5 Povidone 15.0 Croscarmellose sodium 12.0 Microcrystallinecellulose 92.5 Magnesium stearate 3.0 300.0 (ii) Tablet 2 mg/tablet‘Compound X’ 20.0 Microcrystalline cellulose 410.0 Starch 50.0 Sodiumstarch glycolate 15.0 Magnesium stearate 5.0 500.0 (iii) Capsulemg/capsule ‘Compound X’ 10.0 Colloidal silicon dioxide 1.5 Lactose 465.5Pregelatinized starch 120.0 Magnesium stearate 3.0 600.0 (iv) Injection1 (1 mg/ml) mg/ml ‘Compound X’ (free acid form) 1.0 Dibasic sodiumphosphate 12.0 Monobasic sodium phosphate 0.7 Sodium chloride 4.5 1.0 NSodium hydroxide solution q.s. (pH adjustment to 7.0-7.5) Water forinjection q.s. ad 1 mL (v) Injection 2 (10 mg/ml) mg/ml ‘Compound X’(free acid form) 10.0 Monobasic sodium phosphate 0.3 Dibasic sodiumphosphate 1.1 Polyethylene glycol 400 200.0 01 N Sodium hydroxidesolution q.s. (pH adjustment to 7.0-7.5) Water for injection q.s. ad 1mL (vi) Aerosol mg/can ‘Compound X’ 20.0 Oleic acid 10.0Trichloromonofluoromethane 5,000.0 Dichlorodifluoromethane 10,000.0Dichlorotetrafluoroethane 5,000.0 (vii) Tablet 1 mg/tablet ‘Compound X’100.0 β-lactam antibiotic 100.0 Lactose 77.5 Povidone 15.0Croscarmellose sodium 12.0 Microcrystalline cellulose 92.5 Magnesiumstearate 3.0 400.0 (viii) Tablet 2 mg/tablet ‘Compound X’ 20.0 β-lactamantibiotic 20.0 Microcrystalline cellulose 410.0 Starch 50.0 Sodiumstarch glycolate 15.0 Magnesium stearate 5.0 520.0 (ix) Capsulemg/capsule ‘Compound X’ 10.0 β-lactam antibiotic 10.0 Colloidal silicondioxide 1.5 Lactose 465.5 Pregelatinized starch 120.0 Magnesium stearate3.0 610.0 (x) Injection 1 mg/ml ‘Compound X’ (free acid form) 1.0β-lactam antibiotic 2.0 Dibasic sodium phosphate 12.0 Monobasic sodiumphosphate 0.7 Sodium chloride 4.5 1.0 N Sodium hydroxide solution q.s.(pH adjustment to 7.0-7.5) Water for injection q.s. ad 1 mL (xi)Injection 2 mg/ml ‘Compound X’ (free acid form) 10.0 β-lactam antibiotic5.0 Monobasic sodium phosphate 0.3 Dibasic sodium phosphate 1.1Polyethylene glycol 400 200.0 01 N Sodium hydroxide solution q.s. (pHadjustment to 7.0-7.5) Water for injection q.s. ad 1 mL (xii) Aerosolmg/can ‘Compound X’ 20.0 β-lactam antibiotic 20.0 Oleic acid 10.0Trichloromonofluoromethane 5,000.0 Dichlorodifluoromethane 10,000.0Dichlorotetrafluoroethane 5,000.0

The above formulations may be obtained by conventional procedures wellknown in the pharmaceutical art. “β-lactam antibiotic” can be anycompound possessing antibiotic properties (e.g. amoxicillin,piperacillin, ampicillin, ceftizoxime, cefotaxime, cefuroxime,cephalexin, cefaclor, cephaloridine, or ceftazidime). Although specificquantities of “Compound X” and “β-lactam antibiotic” are shown in theabove illustrative examples, it is to be understood that the compoundscan be present in any ratio provided the final formulation possesses thedesired antibiotic properties.

All publications, patents, and patent documents are incorporated byreference herein in their entirety. The invention has been describedwith reference to various specific and preferred embodiments andtechniques. However, it should be understood that many variations andmodifications may be made while remaining within the spirit and scope ofthe invention.

1. A compound of formula (I):

wherein: R₁ and R₂ are each independently hydrogen, (C₁-C₁₀)alkyl,(C₂-C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₃-C₈)cycloalkyl, (C₁-C₁₀)alkoxy,(C₁-C₁₀)alkanoyl, (C₁-C₁₀)alkanoyloxy, (C₁-C₁₀)alkoxycarbonyl, aryl,heterocycle, halo, cyano, nitro, —COOR_(e), —C(═O)NR_(f)R_(g),—OC(═O)NR_(f)R_(g), NR_(f)R_(g), or —S(O)_(n)R_(h); R₃ is—CH═CHC(═O)NR_(m)R_(p); R₄ is hydrogen; A is thio, sulfinyl, orsulfonyl; each n is independently 0, 1, or 2; each R_(e) isindependently hydrogen, or (C₁-C₁₀)alkyl; each R_(f) and R_(g) isindependently hydrogen, (C₁-C₁₀)alkyl, (C₁-C₁₀)alkoxy, phenyl, benzyl,phenethyl, (C₁-C₁₀)alkanoyl, or —C(═O)NR_(f)R_(g) wherein R_(f) andR_(g) form with the N atom to which they are attached a ring optionallycontaining a nitrogen atom in the ring —NR—; each R_(h) is independently(C₁-C₁₀)alkyl, or aryl; and R_(i) is hydrogen or (C₁-C₆)alkyl: and R_(m)is hydrogen, and R_(p) is NH₂, OH, (C₂-C₁₀)cycloalkyl, or—(C₂-C₁₀)alkyl-NH₂; or R_(m), and R_(p) together with the nitrogen towhich they are attached form a piperidine, morpholine, thiomorpholine,pyrrolidine, or piperazine ring, wherein the piperazine is substitutedat the 4-position with hydrogen or a (C₁-C₁₀)alkyl; wherein any(C₁-C₁₀)alkyl, (C₂-C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₃-C₈)cycloalkyl,(C₁-C₁₀)alkoxy, (C₁-C₁₀)alkanoyl, (C₁-C₁₀)alkanoyloxy, or(C₁-C₁₀)alkoxycarbonyl of R₁ or R₂ is optionally substituted with one ormore, substituents independently selected from halo, hydroxy, cyano,cyanato, nitro, mercapto, oxo, aryl, heterocycle, (C₂-C₆)alkenyl,(C₂-C₆)alkynyl, (C₁-C₆)alkoxy, (C₁-C₆)alkanoyl, (C₁-C₆)alkanoyloxy,aryl(C₁-C₆)alkanoyloxy, halo(C₁-C₆)alkanoyloxy,heterocycle(C₁-C₆)alkanoyloxy, aryloxy, (heterocycle)oxy,(C₃-C₈)cycloalkyl, —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g),—NR_(h)R_(i), or —S(O)_(n)R_(h); and wherein any aryl is optionallysubstituted with one or more substituents independently selected fromhalo, hydroxy, cyano, trifluoromethyl, nitro, trifluoromethoxy,(C₁-C₆)alkyl, (C₁-C₆)alkanoyl, (C₁-C₆)alkanoyloxy,(C₁-C₆)alkoxycarbonyl, —COOR_(e), —C(═O)NR_(f)R_(g), —OC(═O)NR_(f)R_(g),NR_(h)R_(i), or —S(O)_(n)R_(h); or a pharmaceutically acceptable saltthereof.
 2. The compound of claim 1 wherein R₁ is aryl, heterocycle, or—COOR_(e).
 3. The compound of claim 1 wherein R₁ is 2-pyridyl, or—COOR_(e).
 4. The compound of claim 1 wherein R₂ is hydrogen. 5-16.(canceled)
 17. The compound of claim 1 wherein R_(h) is methyl orphenyl. 18-20. (canceled)
 21. The compound of claim 1 wherein A issulfonyl.
 22. The compound of claim 1 wherein A is sulfonyl; R₁ is2-pyridyl, carboxy or tert-butoxy carbonyl; and R₂ is hydrogen; or apharmaceutically acceptable salt.
 23. A pharmaceutical compositioncomprising a compound of claim 1; or a pharmaceutically acceptable saltthereof; and a pharmaceutically acceptable carrier.
 24. The compositionof claim 23 further comprising a β-lactam antibiotic.
 25. A methodcomprising inhibiting a β-lactamase by contacting said β-lactamase withan effective amount of a compound of claim
 1. 26. A therapeutic methodcomprising inhibiting a β-lactamase in a mammal in need of such therapy,by administering an effective inhibitory amount of a compound ofclaim
 1. 27. A therapeutic method comprising enhancing the activity of aβ-lactam antibiotic, by administering the β-lactam antibiotic to amammal in need thereof, in combination with an effective β-lactamaseinhibiting amount of a compound of claim
 1. 28. A therapeutic methodcomprising treating a β-lactam resistant bacterial infection in amammal, by administering to the mammal an effective amount of a β-lactamantibiotic, in combination with an effective β-lactamase inhibitingamount of a compound of claim
 1. 29. (canceled)